1. Field of the Disclosure
The present invention relates to a semiconductor device, more particularly, to a bipolar junction transistor (BJT) and a method of manufacturing the same.
2. Discussion of the Related Art
Generally, poly-emitter type bipolar junction transistors are suitable for high speed operation and they are operable in a high frequency range. Generally, a collector current increases in proportion to a reverse saturation current in a normal active mode of such a bipolar junction transistor (BJT).
FIG. 1 is an overhead or layout view illustrating a conventional poly-emitter type bipolar transistor. FIG. 2 is a cross-sectional view of the bipolar junction transistor shown in FIG. 1 along the A-A′ line.
The reverse saturation current in the BJT is determined by a predetermined number of elements. In order to increase current gain while maintaining a base voltage and an emitter voltage that are identical to each other, the reverse saturation current can be increased.
To increase the reverse saturation current, the functional area of the emitter 130, base 120, and collector 110 may each be increased, or the depth of the base 120 may be decreased. However, when the depth of the base is decreased, the depletion layers of the emitter 130 and the collector may be too close and may overlap. Thus, the device characteristics may deteriorate.